Various compositions prepared by the sulfurization of organic compounds and more particularly olefins and olefin-containing compounds are known in the art, as are lubricants containing these products. Typical sulfurized compositions prepared by reacting olefins such as isobutene, diisobutene, and triisobutene with sulfur under various conditions are described in, for example, Chemical Review, 65, 237 (1965). Other references describe the reaction of such olefins with hydrogen sulfide and elemental sulfur to form predominantly mercaptans with sulfides, disulfides and higher polysulfides also being formed as by-products. Reference is made to J. Am. Chem. Soc., 60, 2452 (1938), and U.S. Pat. Nos. 3,221,056, 3,419,614 and 4,191,659. U.S. Pat. No. 3,419,614 describes a process for increasing the yield of mercaptan by carrying out the reaction of olefin with hydrogen sulfide and sulfur at a high temperature in the presence of various basic materials. U.S. Pat. No. 4,191,659 describes the preparation of sulfurized compositions by reaction at superatmospheric pressure of olefins with a mixture of sulfur and hydrogen sulfide in the presence of a catalyst followed by treatment with an alkali metal sulfide. The use of sulfurized natural and synthetic oils as additives in lubricating compositions has been suggested in the art such as in, for example, U.S. Pat. Nos. 2,299,813 and 4,360,438.
In the past, sulfurized sperm oil was used widely as an additive in many lubricant formulations such as in gear oil, worm, and spur gears, automatic transmission fluids, waxing lubricants, and as metal-working additives. Sulfurized sperm oil is especially useful for improving extreme pressure properties while providing excellent "slip" and some degree of rust-inhibition in motor oils, gear lubricants, and rolling oils. However, the sulfurized sperm oils have been replaced in recent years by other sulfurized compositions as a result of the reduction in availability of sperm oil and increased cost. Sulfurized olefins such as those described above do not always exhibit the degree of lubricity which is necessary in many applications.
Sulfurized fatty oils such as sulfurized lard oil have been described in the art, but sulfurized lard oil generally is not adequately soluble in paraffinic base oils to be useful. Several patents have issued in the last decade suggesting solutions to the solubility problems exhibited by sulfurized lard oil. A number of the prior art suggestions have involved sulfurizing mixtures of fatty oils such as lard oil and soybean oil and various olefinic compounds. For example, U.S. Pat. Nos. 3,953,347 and 3,926,822 describe compositions of matter useful as lubricant additives which are sulfurized compositions prepared by reacting sulfur with a mixture comprising at least one fatty acid ester, at least one aliphatic olefin containing about 8 to about 36 carbon atoms and optionally, at least one fatty acid. The sulfurized compositions are prepared by heating such mixtures of fatty acid ester and fatty acid olefin with sulfur at temperatures of from 65 to about 200.degree. C. In addition to the above-described reagent, the reaction mixture may also include sulfurization promoters such as phosphorous-containing reagents such as phosphorous acid esters, and surface-active agents such as lecithin. An example of a phosphorous-acid ester given in these patents is triphenylphosphite.
U.S. Pat. No. 2,012,446 describes a method of sulfurizing pine oil which is reported as being useful as an additive for lubricant manufacture.
U.S. Pat. No. 4,188,300 describes a sulfurized product obtained by sulfurizing an olefin with a prime burning grade lard oil having a very low free acid content. These products are reported to exhibit improved solubility in paraffinic oils as compared to products obtained when an olefin is co-sulfurized with lard oil having a higher content of free acids such as winter-stained lard oil or extra winter-strained lard oil. Co-sulfurized products containing about 5 to 25% by weight of sulfur are obtained and are reported as being useful as metal-working oil additives. The preparation of various synthetic sulfurized oil of the reaction of sulfur, lard oil and polyisobutylene oligomers containing at least one pair of maximally crowded geminal methyl groups (e.g., tetraisobutylene) is described in U.S. Pat. No. 4,166,795. The preparation of synthetic sulfurized oil useful as the replacement for sulfurized sperm oil also is described in U.S. Pat. Nos. 3,843,534; 3,825,495; 4,166,795; 4,166,796; 4,166,797; 4,321,153; 4,456,540; and 4,487,705. The sulfurization generally is carried out using elemental sulfur, and simultaneous sulfurization and chlorination may be effected by reacting with sulfur monochloride. Phosphosulfurization is described in these patents and may be carried out by addition of small amounts of a phosphorus sulfide to the sulfurized blend followed by heating.
When preparing sulfurized compositions for use as lubricant additives, it generally is desirable to obtain products by the most inexpensive procedure utilizing inexpensive raw material. The color of the sulfurized compositions obtained should preferably be light, and the sulfur contained in the products should not be active sulfur.
The present invention also relates to metal working operations and more particularly to lubricants for use during such operations. In its broadest sense, it comprises a method for lubricating metal during working thereof and metal workpieces having on the surface thereof a film of a lubricant composition. Said composition comprises a major amount of a lubricating oil and a minor amount of at least one sulfurized composition prepared in accordance with this invention.
Metal working operations, for example, rolling, forging, hot-pressing, blanking, bending, stamping, drawing, cutting, punching, spinning and the like, generally employ a lubricant to facilitate the same. Lubricants greatly improve these operations in that they can reduce the power required for the operation, prevent sticking and decrease wear of dies, cutting tools and the like. In addition, they frequently provide rust-inhibiting properties to the metal being treated.
Many presently known metal working lubricants are oil-based lubricants containing a relatively large amount of active sulfur present in additives therein. (By "active sulfur" as used herein is meant chemically combined sulfur in a form which causes staining of copper.) The presence of active sulfur is sometimes detrimental because of its tendency to stain copper, as well as other metals including brass and aluminum. Nevertheless, its presence has frequently been necessary because of the beneficial extreme pressure properties of active sulfur-containing compositions, especially for the working of ferrous metals.
The use of sulfur in asphalts is known. Sulfur is generally added to the asphalt composition as elemental sulfur.
The asphalt compositions of this invention are particularly useful for pavements, roadways, driveways, parking lots and the like. The degree and rate of hardening of asphalt cement during application and while in service are factors affecting the durability of a surface such as a road pavement. A certain amount of hardening of a freshly applied surface is often desirable in order to allow the newly placed surface to be placed into service quickly. However, excessive hardening and loss of ductility of an asphalt based surface can dramatically reduce its useful lifetime. Januszke, in "Industrial Engineering Chemistry Product Research and Development", Volume 10, (1971), 209-213, indicates that lead and zinc diethyldithiocarbamates were effective in inhibiting the adverse hardening.
In certain geographic areas, such as desert regions in the western and southwestern United States, deterioration of an asphalt road may occur quickly and is often extensive. Embrittlement and cracking of the road surface often result.
It is known in the art that excessive hardening of paving asphalts can be reduced through the use of certain antioxidants such as lead or zinc dithiocarbamates. The above-mentioned reference by Januszke discusses an evaluation of the effect of 24 antioxidants on paving asphalt durability and is incorporated by reference for its teachings regarding the problem and methods of assessing the performance of additives.
It is also known in the art to incorporate sulfur and certain sulfur containing compounds as extenders for asphalt cement and to improve durability.